Well, without actually reading it, it could be about a new start for the Harry Potter characters. Maybe it's a rewrite of the original story from a different perspective, like starting from a point where a minor character gets more focus and changes the course of events.
It's hard to say for sure without reading it, but it's likely that Harry Potter would still be one of the main characters since it's a Harry Potter fanfiction. He might be portrayed in a different light, though.
One reason to start questioning Harry Potter fanfiction could be the divergence from the original lore. Some fanfictions might change key aspects of the wizarding world, like magic rules or character personalities. For example, if a fanfiction makes Harry a completely different person with no regard for his canon traits, it can be off - putting.
It could also be due to the fact that a large portion of fanfiction focuses on shipping (pairing characters romantically). While shipping can be fun for some, others might feel that it overshadows other aspects of the story. For example, if most fanfictions are just about who Harry should be with instead of exploring the rich magical world further, it can make you question its overall popularity.
Perhaps you could start with 'Was Snape truly redeemed? And did Harry ever fully understand his sacrifices?' These two questions can lead to a deep exploration of the complex relationship between Harry and Snape, delving into the moral and emotional aspects of the story. It can create a fanfiction that focuses on the gray areas of the characters' personalities and actions.
He could also meet some sort of dark wizard or villain that is even more powerful than Voldemort in this new world. This would pose a great threat to Harry and force him to use all of his skills and knowledge, both from his own world and what he's learned in the new one, to defeat the enemy.
Well, it could be about giving a character in the Harry Potter world another opportunity. Maybe Harry gets a second chance at a certain event, like facing Voldemort in a different way. It might also be about a side character getting another chance at life, love, or achieving their goals in the wizarding world.
It could be a rewrite where Harry is raised by someone other than the Dursleys. For example, if he was raised by Sirius Black from the start, his whole outlook on magic and the wizarding world might be different. Sirius would have taught him about his family's noble history and perhaps some dark magic secrets earlier, which could change how Harry approaches challenges at Hogwarts.
It could be Harry Potter himself, as he might be the one to explore the other planet. Hermione would also likely be there, using her vast knowledge to understand the new world. Ron might accompany them as well, providing his loyalty and humor.